Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/50—Amines
  • C08G59/5046—Amines heterocyclic
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
  • C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
  • C07D307/38—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with substituted hydrocarbon radicals attached to ring carbon atoms
  • C07D307/52—Radicals substituted by nitrogen atoms not forming part of a nitro radical

Definitions

• the invention relates to alkylated amines having a high renewable carbon content and the use thereof as hardeners for epoxy resins.
• Amines are used in industry and construction inter alia as hardeners in epoxy resin compositions.
• properties demanded include a high reactivity at low exothermicity and/or fast, problem-free curing at ambient temperatures to afford coatings or bodies having uniform surfaces without clouding, staining or cratering due to blushing.
• the cured bodies or coatings should have a high hardness at low brittleness to resist mechanical stress as well as possible and for optically demanding applications have a high gloss and a low propensity for yellowing.
• the epoxy resin composition has a low viscosity in order that it may be applied as quickly and easily as possible, has good levelling and deaerating properties and, in some cases, readily penetrates into the substrates.
• RCI Renewable Carbon Index
• Hardeners containing amines having a high renewable carbon index are known, for example from U.S. Pat. No. 9,676,898 or WO 2015/124792, which describe bis(aminomethyl)furans and bisfurfurylamines and the use thereof as hardeners for epoxy resins.
• these amines are costly and inconvenient to produce, prone to blushing and their diluting effect on the epoxy resin is in need of improvement.
• EP 3,350,245 discloses sustainable hardeners containing alkylated amines having a tetrahydrofuran ring. These hardeners show incomplete curing with reduced final hardness, especially in two-dimensional application and under low-temperature conditions, for example 8° C.
• Benzylated amines are also known, for example from EP 2 731 927, EP 3 180 383 or EP 3 344 677.
• these amines have a good dilution effect and allow fast, trouble-free curing, even in the case of two-dimensional application and low ambient temperatures.
• biobased production thereof is not possible.
• RCI renewable carbon index
• the amine of formula (I) is obtained in a simple process from the reductive alkylation of a primary aliphatic amine with furfural based on renewable raw materials.
• the amine of formula (I) has a high RCI, preferably at least 0.45, in particular at least 0.7.
• the hardener containing the amine of formula (I) is capable of surprisingly high dilution.
• the epoxy resin is diluted particularly efficiently, even more highly than with the known N-benzyl-1,2-ethanediamine. This is surprising because the amount of N-furfuryl-1,2-ethanediamine required to cure the epoxy resin is lower than for N-benzyl-1,2-ethanediamine due to the lower amine equivalence weight and a lower diluting effect than for N-benzyl-1,2-ethanediamine would be expected due to the oxygen in the furan ring and the resulting possibility of hydrogen bridge formation.
• the hardener according to the invention is very low-odor which is a further great advantage for many applications. It enables fast and trouble-free curing to a high final hardness. What is particularly surprising is the low exothermicity during curing which is markedly lower than when using N-benzyl-1,2-ethanediamine, the processing times and curing rates with N-furfuryl-1,2-ethandiamine being only insubstantially longer/slower than with N-benzyl-1,2-ethanediamine.
• the low exothermicity allows use in epoxy resin products employed in thick layers such as shaped bodies, potting compounds or matrix resins for composites, without occurrence of blisters, discoloration or other inhomogeneities owing to high evolution of heat.
• the hardener makes it possible to achieve epoxy resin coatings curable at ambient temperatures with attractive, glossy surfaces and only very low propensity for blushing effects. It is also particularly surprising that N-furfuryl-1,2-ethanediamine may also be used in the form of a little-purified, particularly inexpensively producible reaction product without appreciable adverse effects during curing of the epoxy resins.
• the invention provides for use of a hardener containing at least one amine of formula (I) for curing of epoxy resins,
• A represents a linear alkylene radical having 2 to 10 carbon atoms and X represents H or furfuryl.
• RCI is the “Renewable Carbon Index” of a substance or a mixture of substances, wherein the RCI is the ratio of the number of carbon atoms from biobased sources to the total number of carbon atoms of the substance or the mixture of substances.
• a “primary amino group” refers to an amino group that is attached to a single organic radical and bears two hydrogen atoms;
• a “secondary amino group” refers to an amino group that is attached to two organic radicals, which may also together be part of a ring, and bears one hydrogen atom;
• tertiary amino group refers to an amino group that is attached to three organic radicals, two or three of which may also be part of one or more rings, and does not bear any hydrogen atoms.
• Amine hydrogen refers to the hydrogen atoms of primary and secondary amine groups.
• “Amine hydrogen equivalent weight” refers to the mass of an amine or an amine-containing composition that contains one molar equivalent of amine hydrogen. It is expressed in units of “g/eq”.
• epoxy equivalent weight refers to the mass of an epoxy group-containing compound or composition that contains one molar equivalent of epoxy groups. It is expressed in units of “g/eq”.
• Substance names beginning with “poly”, such as polyamine or polyepoxide, refer to substances that formally contain two or more of the functional groups that occur in their name per molecule.
• a “diluent” refers to a substance that is soluble in an epoxy resin and lowers its viscosity and that is not chemically incorporated into the epoxy resin polymer during the curing process.
• Molecular weight refers to the molar mass (in grams per mole) of a molecule.
• Average molecular weight refers to the number-average M n of a polydisperse mixture of oligomeric or polymeric molecules, which is normally determined by gel-permeation chromatography (GPC) against polystyrene as standard.
• Solid life refers to the maximum period of time from the mixing of the components to the application of an epoxy resin composition in which the mixed composition is in a sufficiently free-flowing state and has good ability to wet the substrate surfaces.
• the “gel time” is the time interval from the mixing of the components of an epoxy resin composition to gelation thereof.
• Root temperature refers to a temperature of 23° C.
• Percent by weight (% by weight) values refer to the mass fractions of a constituent in a composition based on the overall composition, unless otherwise stated.
• the terms “mass” and “weight” are used synonymously in the present document.
• A preferably represents 1,2-ethylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,6-hexylene, 1,7-heptylene, 1,8-octylene, 1,9-nonylene or 1,10-decylene.
• A is particularly preferably selected from the group consisting of 1,2-ethylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene and 1,6-hexylene. These amines are obtainable particularly simply and with high RCI and have particularly good compatibility with epoxy resins.
• A most preferably represents 1,2-ethylene.
• Such an amine of formula (I) makes it possible to achieve epoxy resin compositions with particularly fast and trouble-free curing and has a particularly high RCI, even in the event that the carbon atoms from the radical A do not originate from a biobased source.
• the amine of formula (I) is selected from the group consisting of N-furfuryl-1,2-ethanediamine, N,N′-difurfuryl-1,2-ethanediamine, N-furfuryl-1,3-propanediamine, N,N′-difurfuryl-1,3-propanediamine, N-furfuryl-1,4-butanediamine, N,N′-difurfuryl-1,4-butanediamine, N-furfuryl-1,5-pentanediamine, N,N′-difurfuryl-1,5-pentanediamine, N-furfuryl-1,6-hexanediamine and N,N′-difurfuryl-1,6-hexanediamine.
• N-furfuryl-1,2-ethanediamine or N,N′-difurfuryl-1,2-ethanediamine.
• N-Furfuryl-1,2-ethanediamine is particularly preferred.
• the amine of formula (I) is employed as a mixture of amine of formula (I) where X ⁇ H and amine of formula (I) where X ⁇ furfuryl in a weight ratio in the range from 50/50 to 98/2, in particular 60/40 to 95/5.
• a mixture is particularly inexpensively producible and allows fast and trouble-free curing of the epoxy resin.
• the amine of formula (I) is preferably produced by reductive alkylation of at least one amine of formula H 2 N-A-NH 2 with furfural and hydrogen.
• Furfural is preferably based on renewable raw materials and has an RCI of 1. This allows amines of formula (I) having a high RCI.
• furfural typically originates from a biobased source.
• furfural is obtained for example from hemicellulose from vegetable materials, in particular by the action of sulfuric acid on the C5 sugars present therein in a dehydration, or in pulp production according to the magnesium bisulfite process, where liberated furfural can be extracted from the black liquor.
• Preferred amines of formula H 2 N-A-NH 2 are 1,2-ethanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine or 1,6-hexanediamine, in particular 1,2-ethanediamine.
• the carbon atoms of the amine of formula H 2 N-A-NH 2 also originate from a renewable source. This makes it possible to achieve very particularly sustainable amines of formula (I), in particular having an RCI of 1. It is preferable when the amine of formula (I) has an RCI of at least 0.45, preferably at least 0.6, in particular at least 0.7, most preferably of 1.
• the reductive alkylation is preferably performed in the presence of a suitable catalyst.
• Preferred catalysts are palladium on charcoal (Pd/C), platinum on charcoal (Pt/C), Adams' catalyst or Raney nickel, especially palladium on charcoal or Raney nickel.
• the reductive alkylation is preferably performed in a pressure apparatus at a hydrogen pressure of 5 to 120 bar, in particular 10 to 100 bar. This may be effected in a batchwise process or preferably in a continuous process.
• the reductive alkylation is preferably performed at a temperature in the range from 40° C. to 120° C., especially 60° C. to 100° C.
• the obtained reaction mixture contains different proportions of monoalkylated amine of formula H 2 N-A-NH 2 , i.e. amine of formula (I) where X ⁇ H, and dialkylated amine of formula H 2 N-A-NH 2 , i.e. amine of formula (I) where X ⁇ furfuryl.
• an amine of formula (I) where X ⁇ furfuryl is to be produced the molar ratio of the amine of formula H 2 N-A-NH 2 to furfural is preferably in the range from 0.4 to 0.7, in particular 0.5.
• a thus-obtained reaction mixture contains a particularly high content of amine of formula (I) where X ⁇ furfuryl.
• an amine of formula (I) where X ⁇ H is to be produced the molar ratio of the amine of formula H 2 N-A-NH 2 to furfural is preferably in the range from 1 to 10, in particular 1 to 5.
• a thus-obtained reaction mixture contains a high content of amine of formula (I) where X ⁇ H.
• Excess amine of formula H 2 N-A-NH 2 is preferably removed from the reaction mixture after the reaction, in particular by distillation together with the released water.
• the reaction mixture may be further purified, in particular by distillation/fractionation.
• the amine of formula (I) may be freed of the byproducts and/or the amine of formula (I) where X ⁇ H may be separated from the amine of formula (I) where X ⁇ furfuryl.
• the amine of formula (I) is employed in the form of a reaction product obtained from the reductive alkylation of at least one amine of formula H 2 N-A-NH 2 with furfural and hydrogen and subsequent removal of unreacted amine of formula H 2 N-A-NH 2 .
• the reaction product is preferably not further purified, in particular a distillation/fractionation of the amines of formula (I) is eschewed.
• Such a reaction product is producible particularly inexpensively. It contains a low content of amine of formula H 2 N-A-NH 2 , preferably less than 2% by weight, particularly preferably less than 1% by weight, especially less than 0.5% by weight, of amine of formula H 2 N-A-NH 2 based on the total reaction product.
• the reaction product may contain byproducts from the reductive alkylation, in particular amines having di- or tri-alkylated nitrogen atoms, and amines having a hydrogenated furan ring. These proportions are preferably low.
• reaction product has a content of amines having di- or tri-alkylated nitrogen atoms, in particular of formulae
• reaction product has a content of amines having a hydrogenated furan ring, in particular of formulae
• the amine of formula (I) is obtained in the form of a reaction product from the reductive alkylation of at least one amine of formula H 2 N-A-NH 2 with furfural and hydrogen and subsequent removal of unreacted amine of formula H 2 N-A-NH 2 , wherein the molar ratio of the amine of formula H 2 N-A-NH 2 to furfural is in the range from 1 to 2, preferably 1 to 1.5. It is preferable when A represents 1,2-ethylene.
• the content of amine of formula H 2 N-A-NH 2 in this reaction product is preferably at most 1% by weight, particularly preferably at most 0.5% by weight, in particular at most 0.2% by weight, based on the total reaction product.
• Such a reaction product contains a surprisingly high content of amine of formula (I) where X ⁇ H and surprisingly little amine of formula (I) where X ⁇ furfuryl and has a surprisingly high reactivity towards the epoxy resin which is hardly inferior to that of the largely pure amine of formula (I) where X ⁇ H.
• a corresponding reaction of 1,2-ethanediamine with benzaldehyde instead of furfural has a massively higher content of N,N′-dialkylated 1,2-ethanediamine at a corresponding stoichiometry.
• the weight ratio between the amine of formula (I) where X ⁇ H and the amine of formula (I) where X ⁇ furfuryl in the reaction product is in the range from 50/50 to 98/2, preferably 60/40 to 95/5, based on the reaction product.
• the invention thus further provides the reaction product obtained from the reductive alkylation of an amine of formula H 2 N-A-NH 2 with furfural and hydrogen in a molar ratio of the amine of formula H 2 N-A-NH 2 to furfural in the range from 1 to 2, preferably 1 to 1.5, and subsequent removal of amine of formula H 2 N-A-NH 2 to a content of at most 1% by weight, preferably at most 0.5% by weight, in particular at most 0.2% by weight, based on the reaction product, wherein A represents a linear alkylene radical having 2 to 10 carbon atoms, in particular 1,2-ethylene.
• reaction product contains 50% to 80% by weight of N-furfuryl-1,2-ethanediamine, 5% to 50% by weight, in particular 5% to 40% by weight, of N,N′-difurfuryl-1,2-ethanediamine,
• Such a reaction product is easily and inexpensively producible and without further purification very well suited as a constituent of a hardener for hardening of epoxy resins, wherein said product has a high reactivity towards the epoxy resin which is hardly inferior to that of substantially pure N-furfuryl-1,2-ethanediamine.
• Such an amine mixture is simple to produce and allows surprisingly fast and trouble-free curing of the epoxy resin.
• the invention thus further provides an amine mixture containing at least one amine of formula
• A represents a linear alkylene radical having 2 to 10 carbon atoms, in particular 1,2-ethylene.
• the amine of formula (I) is used partially or completely in the form of an amine-functional adduct with at least one epoxy resin or monoepoxide in a stoichiometric ratio of at least 1 mol of amine of formula (I) to 1 mol equivalent of epoxy groups.
• Such an adduct is in the form of a mixture of adducted molecules having at least two, typically having 3 or 4, amine hydrogens derived from the amine of formula (I) and free, non-adducted amine of formula (I). It allows particularly fast curing at moderate viscosity, especially also at low temperatures of 8° C.
• the epoxy resin preferably has an average epoxy equivalent weight in the range from 150 to 500 g/eq, preferably 156 to 250 g/eq.
• aromatic epoxy resins having an average functionality in the range from 2 to 4, in particular a bisphenol A, F or A/F diglycidyl ether or a novolac epoxy resin. These adducts allow particularly fast curing and high glass transition temperatures.
• epoxy resins having polyoxypropylene and/or polyoxyethylene units are especially diglycidyl ethers of polypropylene glycols or reaction products of bisphenol A, F or A/F diglycidyl ethers with polypropylene glycols or polyethylene glycols. Such adducts are particularly suitable as a constituent of water-based hardeners for epoxy resins.
• aromatic diepoxides in particular a bisphenol A, F or A/F diglycidyl ether.
• adducting is carried out in a stoichiometric ratio in the range from 1 to 10, preferably 1.2 to 5, in particular 1.4 to 3, mol of amine of formula (I) per molar equivalent of epoxy groups.
• the hardener preferably contains at least one further constituent selected from further amines which do not conform to formula (I), accelerators and diluents, in particular at least one further amine which does not conform to formula (I).
• the hardener contains at least one further amine which does not conform to formula (I) and which is not a byproduct from the production of the amine of formula (I).
• Preferred further amines which do not conform to formula (I) are amines having aliphatic amino groups and at least three amine hydrogens, in particular N-benzyl-1,2-ethanediamine, N-benzyl-1,2-propanediamine, N-benzyl-1,3-bis(aminomethyl)benzene, N-(2-ethylhexyl)-1,3-bis(aminomethyl)benzene, 2,2-dimethyl-1,3-propanediamine, 1,3-pentanediamine (DAMP), 1,5-pentanediamine, 1,5-diamino-2-methylpentane (MPMD), 2-butyl-2-ethyl-1,5-pentanediamine (C11-neodiamine), 1,6-hexanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,2(4),4-trimethyl-1,6-hexanediamine (TMD), 1,7-heptanediamine, 1,8-octanedia
• the hardener preferably contains at least one amine selected from the group consisting of N-benzyl-1,2-ethanediamine, N,N′-dibenzyl-1,2-ethanediamine, MPMD, TMD, 1,2-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, IPDA, 2(4)-methyl-1,3-diaminocyclohexane, MXDA, DETA, TETA, TEPA, N3-amine, N4-amine, DPTA, BHMT, polyoxypropylenediamines having an average molecular weight M n in the range from 200 to 500 g/mol, polyoxypropylenetriamines having an average molecular weight M n in the range from 300 to 500 g/mol, 2,5-bis(aminomethyl)furan, 2,5-bis
• 1,3-bis(aminomethyl)cyclohexane or 1,4-bis(aminomethyl)cyclohexane especially 1,3-bis(aminomethyl)cyclohexane. This permits particularly rapid curing.
• IPDA IP-based acetone
• MXDA metal-oxide-semiconductor
• N-benzyl-1,2-ethanediamine is N-benzyl-1,2-ethanediamine.
• Such a hardener allows particularly low-viscosity epoxy resin products with particularly attractive surfaces.
• 2,5-bis(aminomethyl)furan 2,5-bis(aminomethyl)tetrahydrofuran, bis(5-aminomethylfuran-2-yl)methane, bis(5-aminomethyltetrahydrofuran-2-yl)methane, 2,2-bis(5-aminomethylfuran-2-yl)propane or 2,2-bis(5-aminomethyltetrahydrofuran-2-yl)propane, in particular 2,5-bis(aminomethyl)furan.
• This makes it possible to achieve particularly sustainable hardeners.
• the hardener may in particular contain more than one further amine which does not conform to formula (I).
• the hardener particularly preferably contains as a further amine which does not conform to formula (I) at least one amine having an RCI of 1, in particular selected from 2,5-bis(aminomethyl)furan, 2,5-bis(aminomethyl)tetrahydrofuran, bis(5-aminomethylfuran-2-yl)methane, bis(5-aminomethyltetrahydrofuran-2-yl)methane, 2,2-bis(5-aminomethylfuran-2-yl)propane and 2,2-bis(5-aminomethyltetrahydrofuran-2-yl)propane.
• RCI 1, in particular selected from 2,5-bis(aminomethyl)furan, 2,5-bis(aminomethyl)tetrahydrofuran, bis(5-aminomethylfuran-2-yl)methane, bis(5-aminomethyltetrahydrofuran-2-yl)methane, 2,2-bis(5-aminomethylfuran
• the hardener contains an amount of further amines which do not conform to formula (I) such that 5% to 95%, preferably 10% to 80%, in particular 15% to 60%, of all amine hydrogens present originate from amines of formula (I).
• the amine of formula (I) is present in the form of an adduct with an epoxy resin the amine hydrogens of such adducts are likewise counted as amine hydrogens of the amine of formula (I).
• Suitable accelerators are especially acids or compounds hydrolyzable to acids, especially organic carboxylic acids such as acetic acid, benzoic acid, salicylic acid, 2-nitrobenzoic acid, lactic acid, organic sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid or 4-dodecylbenzenesulfonic acid, sulfonic esters, other organic or inorganic acids, such as phosphoric acid in particular, or mixtures of the abovementioned acids and acid esters; nitrates such as calcium nitrate in particular; tertiary amines such as, in particular, 1,4-diazabicyclo[2.2.2]octane, benzyldimethylamine, ⁇ -methylbenzyldimethylamine, triethanolamine, dimethylaminopropylamine, imidazoles such as, in particular, N-methylimidazole, N-vinylimidazole or 1,2-di
• acids Preference is given to acids, nitrates, tertiary amines or Mannich bases, especially salicylic acid, calcium nitrate or 2,4,6-tris(dimethylaminomethyl)phenol, or a combination of these accelerators.
• Suitable diluents are especially n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, n-hexanol, 2-ethylhexanol, xylene, 2-methoxyethanol, dimethoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, 2-phenoxyethanol, 2-benzyloxyethanol, benzyl alcohol, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol diphenyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-
• diluents having a boiling point of more than 200° C. especially benzyl alcohol, styrenated phenol, ethoxylated phenol, aromatic hydrocarbon resins containing phenol groups, such as in particular the Novares® grades LS 500, LX 200, LA 300 or LA 700 (from Ruitgers), diisopropylnaphthalene or cardanol, especially benzyl alcohol.
• Phenol-containing diluents are also effective as accelerators.
• aromatic diluents having a particularly high diluting effect, especially xylene.
• the hardener preferably contains only a small content of diluents, in particular 0% to 50% by weight, preferably 0% to 30% by weight, of diluents based on the overall hardener.
• the hardener preferably contains 1% to 99% by weight, more preferably 5% to 90% by weight, more preferably 10% to 80% by weight, particularly preferably 15% to 70% by weight, of amines of formula (I) based on the overall hardener.
• the hardener may be water-based and contain water in the range from 15% to 90% by weight, preferably 20% to 80% by weight.
• the hardener is preferably not water-based. It preferably contains less than 15% by weight, especially less than 10% by weight, of water, based on the overall hardener. Such a hardener is particularly suitable for nonaqueous epoxy resin products.
• the hardener may contain further constituents, especially:
• the invention further provides an epoxy resin composition comprising
• a suitable epoxy resin is obtained in a known manner, especially from the reaction of epichlorohydrin with polyols, polyphenols or amines.
• Suitable epoxy resins are especially aromatic epoxy resins, especially the glycidyl ethers of:
• epoxy resins are aliphatic or cycloaliphatic polyepoxides, especially
• epoxy resins having a high RCI especially those from the reaction of biobased hydroxy-functional raw materials with epichlorohydrin.
• vanillin-based epoxy resins such as especially diglycidyl ethers of vanillin alcohol and glycerol-based epoxy resins such as especially triglycidyl ethers of biobased glycerol.
• the epoxy resin is preferably a liquid resin or a mixture containing two or more liquid epoxy resins.
• Liquid epoxy resin refers to an industrial polyepoxide having a glass transition temperature below 25° C.
• the resin component optionally additionally contains proportions of solid epoxy resin.
• the epoxy resin is especially a liquid resin based on a bisphenol or novolac, especially having an average epoxy equivalent weight in the range from 156 to 210 g/eq.
• a bisphenol A diglycidyl ether and/or bisphenol F diglycidyl ether such as are commercially available for example from Olin, Huntsman or Momentive.
• These liquid resins have low viscosity for epoxy resins and permit rapid curing and high hardnesses. They may contain proportions of solid bisphenol A resin or novolac epoxy resins.
• phenol-formaldehyde novolac glycidyl ethers especially having an average functionality in the range from 2.3 to 4, preferably 2.5 to 3.
• These may contain proportions of other epoxy resins, in particular bisphenol A diglycidyl ether or bisphenol F diglycidyl ether.
• diglycidyl ethers of vanillin alcohol or triglycidyl ethers of glycerol, in particular diglycidyl ethers of vanillin alcohol.
• the resin component may comprise a reactive diluent.
• Preferred reactive diluents are reactive diluents containing epoxy groups, especially butanediol diglycidyl ether, hexanediol diglycidyl ether, trimethylolpropane di- or triglycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, guaiacol glycidyl ether, 4-methoxyphenyl glycidyl ether, p-n-butylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, 4-nonylphenyl glycidyl ether, 4-dodecylphenyl glycidyl ether, cardanol glycidyl ether, benzyl glycidyl ether, allyl glycidyl ether, butyl glycid
• the epoxy resin composition contains at least one further constituent selected from the group consisting of diluents, accelerators, fillers, pigments, and surface-active additives.
• Suitable diluents or accelerators especially include those mentioned hereinabove.
• Suitable fillers are, in particular, ground or precipitated calcium carbonate, which is optionally coated with fatty acid, especially stearates, baryte (heavy spar), talc, quartz powder, quartz sand, silicon carbide, iron mica, dolomite, wollastonite, kaolin, mica (potassium aluminum silicate), molecular sieves, aluminum oxide, zinc oxide, aluminum-doped zinc oxide, aluminum hydroxide, magnesium hydroxide, silica, cement, gypsum, fly ash, carbon black, graphite, metal powders such as aluminum, copper, iron, zinc, silver or steel, PVC powder or hollow beads. Preference among these is given to calcium carbonate, baryte, quartz powder, talc, aluminum powder or a combination thereof.
• Suitable pigments especially include titanium dioxides, iron oxides, chromium(III) oxides, organic pigments, carbon black or anticorrosion pigments, especially phosphates, orthophosphates or polyphosphates containing especially chromium, zinc, aluminum, calcium, strontium or a combination of these metals as counterions. Titanium dioxides are particularly suitable.
• Suitable surface-active additives are especially defoamers, deaerating agents, wetting agents, dispersants, levelling agents and/or dispersed paraffin waxes.
• the epoxy resin composition may optionally comprise further auxiliaries and additives, especially the following:
• the epoxy resin composition preferably has only a low content of diluents. It preferably contains less than 20% by weight, particularly preferably less than 10% by weight, in particular less than 5% by weight, most preferably less than 1% by weight, of diluent.
• the epoxy resin composition is water-based.
• the epoxy resin is preferably emulsified in an amount of 50% to 85% by weight in water and the hardener component preferably contains 20% to 80% by weight of water.
• the epoxy resin composition preferably contains only a low content of water, preferably less than 5% by weight, especially less than 1% by weight, of water, however.
• a non-water-based epoxy resin composition is particularly versatile and particularly water-resistant.
• the resin component and the hardener component of the epoxy resin composition are stored in separate receptacles.
• a suitable receptacle for storage of the resin component or the hardener component is in particular a vat, a hobbock, a bag, a bucket, a can, a cartridge or a tube.
• the components are storable, meaning that they can be stored prior to use for several months up to one year or longer without any change in their respective properties to a degree relevant to their use.
• the resin component and hardener component are mixed shortly before or during application.
• the mixing ratio is preferably chosen such that the molar ratio of epoxy-reactive groups to epoxy groups is in the range from 0.5 to 1.5, especially 0.7 to 1.2.
• the mixing ratio between the resin component and the hardener component is typically within a range from 1:2 to 20:1.
• the components are mixed continuously or in batches by means of a suitable method, taking care to ensure that not too much time elapses between the mixing of the components and the application, and that application takes place within the pot life.
• Mixing and application can be effected at ambient temperature, which is typically in the range from about 5° C. to 40° C., preferably about 10° C. to 35° C., or at elevated temperature, especially in the range from 40° C. to 150° C., preferably 50° C. to 120° C.
• the curing of the epoxy resin composition by chemical reaction commences.
• the composition polymerizes and thereby cures.
• Curing typically extends over a few hours to days. The duration depends on factors including the temperature, the reactivity of the constituents, the stoichiometry thereof, and the presence/amount of accelerators.
• the epoxy resin composition has a low viscosity.
• the viscosity 5 minutes after mixing of the resin component and the hardener component at 20° C. is preferably in the range from 0.1 to 20 Pa-s, preferably 0.2 to Pa-s, particularly preferably 0.3 to 5 Pa-s, measured using a cone-plate viscometer at a shear rate of 10 s ⁇ 1 .
• the epoxy resin composition is applied to at least one substrate and/or to at least one casting mold.
• Suitable substrates are especially:
• the substrates can if required be pretreated prior to application, especially by physical and/or chemical cleaning methods or the application of an activator or a primer.
• the substrates are especially coated and/or adhesively bonded.
• a suitable casting mold is an apparatus into which the mixed, liquid epoxy resin composition can be poured and in which it can be cured, and from which it can be demolded or removed after curing, where the cured composition forms a shaped body.
• the casting mold preferably consists at least of a material on the surface, from which the cured epoxy resin composition can be parted again without damage, especially made of metal, ceramic, plastic or silicone, optionally provided with a nonstick coating, especially of Teflon, silicone or a wax.
• the invention further provides a cured composition obtained from the epoxy resin composition described after mixing of the resin component and the hardener component.
• the epoxy resin composition is preferably used as a coating, primer, adhesive, sealant, potting compound, casting resin, impregnating resin, or as a shaped body or matrix for composite materials such as, in particular, CFRP (containing carbon fibers) or GFRP (containing glass fibers) or wood composites.
• CFRP containing carbon fibers
• GFRP containing glass fibers
• the use forms an article containing the cured composition composed of the described epoxy resin composition.
• the article is in particular a floor coating, wall coating, component coating, pipe coating, roof coating or an anticorrosion coating or an adhesive-bonded article or a shaped body, in particular a composite material.
• SCC Standard climatic conditions
• Viscosity was measured on a thermostated Rheotec RC30 cone-plate viscometer (cone diameter 50 mm, cone angle 1°, cone tip-plate distance 0.05 mm, shear rate s ⁇ 1 ). Viscosities of less than 100 mPa-s were measured with a shear rate of 100 s ⁇ 1 .
• Amine number was determined by titration (with 0.1 N HClO 4 in acetic acid against crystal violet).
• GC Gas chromatograms
• FT-IR Infrared spectra
• Reaction Product P-1 (Containing N-furfuryl-1,2-ethanediamine; 1:1 Stoichiometry)
• the reaction mixture was mixed with 1000 ml of isopropanol and then hydrogenated in a continuous hydrogenation apparatus with a Raney nickel fixed bed catalyst at a hydrogen pressure of 70 bar, a temperature of 70° C. and a flow rate of 5.5 ml/min. To monitor the reaction, IR spectroscopy was used to check whether the imine band at approx. 1665 cm ⁇ 1 had disappeared.
• the hydrogenated solution was then concentrated on a rotary evaporator at 65° C. to remove unreacted 1,2-ethanediamine, water and isopropanol.
• the reaction mixture thus obtained was a clear, slightly yellowish liquid having an amine number of 695 mg KOH/g, a viscosity at 20° C.
• Reaction Product P-2 (Containing N-furfuryl-1,2-ethanediamine; 2:1 Stoichiometry)
• the reaction mixture was mixed with 1000 ml of isopropanol and then hydrogenated in a continuous hydrogenation apparatus with a Raney nickel fixed bed catalyst at a hydrogen pressure of 70 bar, a temperature of 70° C. and a flow rate of 5.5 ml/min. To monitor the reaction, IR spectroscopy was used to check whether the imine band at approx. 1665 cm ⁇ 1 had disappeared.
• the hydrogenated solution was then concentrated on a rotary evaporator at 65° C. to remove unreacted 1,2-ethanediamine, water and isopropanol.
• the reaction mixture thus obtained was a clear, slightly yellowish liquid having an amine number of 772 mg KOH/g, a viscosity at 20° C. of 11 mPa-s and a GC-determined content of N-furfuryl-1,2-ethanediamine of about 78.2% by weight (retention time 7.3 min), N-tetrahydrofurfuryl-1,2-ethanediamine of about 12.3% by weight (retention time 8.0 min) and N,N′-difurfuryl-1,2-ethanediamine of about 9.1% by weight (retention time 11.9 min).
• an AHEW 56.6 g/eq was employed.
• Reaction Product P-3 (Containing N-furfuryl-1,2-ethanediamine; 3:1 Stoichiometry)
• the reaction mixture was mixed with 1000 ml of isopropanol and then hydrogenated in a continuous hydrogenation apparatus with a Raney nickel fixed bed catalyst at a hydrogen pressure of 65 bar, a temperature of 65° C. and a flow rate of 5.5 ml/min. To monitor the reaction, IR spectroscopy was used to check whether the imine band at approx. 1665 cm ⁇ 1 had disappeared.
• the hydrogenated solution was then concentrated on a rotary evaporator at 65° C. to remove unreacted 1,2-ethanediamine, water and isopropanol.
• the reaction mixture thus obtained was a clear, slightly yellowish liquid having an amine number of 757 mg KOH/g, a viscosity at 20° C.
• N-furfuryl-1,2-ethanediamine of 10 mPa-s and a GC-determined content of N-furfuryl-1,2-ethanediamine of about 86.1% by weight (retention time 7.3 min), N-tetrahydrofurfuryl-1,2-ethanediamine of about 3.3% by weight (retention time 8.0 min), N,N′-difurfuryl-1,2-ethanediamine of about 2.8% by weight (retention time 11.9 min), proportions of furan ring-hydrogenated N,N′-difurfuryl-1,2-ethanediamine of about 1.5% by weight (retention time 12.5 min) and N,N,N′-trisfurfuryl-1,2-ethanediamine of about 6.0% by weight (retention time 14.2 min).
• an AHEW of 51.6 g/eq was employed.
• FT-IR 3284, 3043, 2945, 2838, 1567, 1504, 1455, 1382, 1306, 1219, 1146, 1108, 1073, 1009, 916, 883, 806, 738.
• THF-EDA N-Tetrahydrofurfuryl-1,2-ethanediamine
• a round-bottomed flask was initially charged with 60.1 g (1 mol) of ethane-1,2-diamine under a nitrogen atmosphere at room temperature.
• a solution of 32.0 g (0.33 mol) of furfural in 200 ml of isopropanol was slowly added dropwise with good stirring and stirring was continued at 40° C. for a further 1 hour.
• the reaction mixture was admixed with a further 300 ml of isopropanol and then hydrogenated in a continuous hydrogenation apparatus with a Raney nickel fixed bed catalyst at a hydrogen pressure of 90 bar, a temperature of 110° C. and a flow rate of 5 ml/min.
• IR spectroscopy was used to check whether the imine band at approx. 1665 cm ⁇ 1 had disappeared.
• the hydrogenated solution was then concentrated on a rotary evaporator at 65° C. to remove unreacted 1,2-ethanediamine, water and isopropanol.
• the reaction mixture thus obtained was a clear, pale yellowish liquid having a GC-determined content of N-benzyl-1,2-ethanediamine of about 81% by weight (retention time 8.5 min) and of N,N′-dibenzylethane-1,2-diamine of about 14% by weight (retention time 14.3 min).
• Said mixture was purified by distillation at 80° C. under reduced pressure. This afforded a colorless liquid having an AHEW of 50.1 g/eq and a GC-determined content of N-benzyl-1,2-ethanediamine of >97% which was hereinbelow employed as B-EDA.
• Adduct A3 (Ref.):
• the resin component and hardener component specified in table 1 were heated separately to a temperature of 60° C. These preheated components were then used to produce a portion of altogether 20 g of epoxy resin composition by mixing the components in the weight ratio specified in table 1 using a centrifugal mixer (SpeedMixerTM DAC 150, FlackTek Inc.) for 15 seconds and then immediately performing testing as follows:
• the mixed composition was introduced into a test tube thermostatted to 60° C. using a water bath and a temperature sensor was positioned in the middle of the mixed material. This was used to determine the time until attainment of the maximum temperature (reported in the table as time to peak exotherm) and the maximum temperature level (peak exotherm temperature) in the mixed material.
• the values given in table 1 are average values from three measurements.
• the Tg value (glass transition temperature) was measured by DSC on cured samples from the middle of the test tube from the above-described determination, and these samples were additionally stored under standard climatic conditions before the measurement for 14 days.
• the epoxy resin composition Z-1 is an inventive example.
• the epoxy resin compositions Ref-1 to Ref-3 are comparative examples.
• the ingredients of the resin component reported in tables 2 to 4 were mixed in the specified amounts (in parts by weight) using a centrifugal mixer (SpeedMixerTM DAC 150, FlackTek Inc.) and stored with exclusion of moisture.
• the ingredients of the hardener component specified in tables 2 to 4 were also processed and stored.
• Viscosity was measured as described at a temperature of 20° C. 5 min after mixing the resin component and the hardener component.
• Gel time was determined by moving a freshly mixed amount of about 3 g under standard climatic conditions with a spatula at regular intervals until the mass underwent gelation.
• Shore D hardness was determined in accordance with DIN 53505 on two cylindrical test specimens (diameter 20 mm, thickness 5 mm), one of which was stored under standard climatic conditions and the other at 8° C. and 80% relative humidity, and the hardness measured in each case after 1 day (24 h) and after 2 days.
• a film was applied to a glass plate in a layer thickness of 500 m, and this was stored/cured under standard climatic conditions. König's hardness (König's pendulum hardness to DIN EN ISO 1522) was determined on this film after 1 day, 2 days, 7 days and 14 days (1d SCC), (2d SCC), (7d SCC), (14d SCC). After 14 days, the appearance (SCC) of the film was assessed. A clear film was described as “attractive” if it had a glossy and nontacky surface with no structure. “Structure” refers to any kind of marking or pattern on the surface.
• a further film was applied to a glass plate in a layer thickness of 500 m and, immediately after application, stored/cured at 8° C. and 80% relative humidity for 7 days and then under standard climatic conditions for 2 weeks. 24 hours after application, a polypropylene bottle top beneath which a damp sponge had been positioned was placed on the film. After a further 24 hours, the sponge and the bottle top were removed and positioned at a new point on the film, from which they were in turn removed and repositioned after 24 hours, this being done a total of 4 times. The appearance of this film was then assessed (referred to as “appearance (8°/80%)” in the tables) in the same way as described for appearance (SCC).
• the epoxy resin compositions Z-2 to Z-10 are inventive examples.
• the epoxy resin compositions Ref-4 to Ref-8 are comparative examples.
• Example Z-5 Ref-7 Z-6 Ref-8 Resin component Araldite ® GY-250 167.2 167.2 167.2 167.2 Araldite ® DY-E 31.8 31.8 31.8 31.8 31.8 31.8 Hardener component: F-EDA 33.1 — 14.5 — B-EDA — 35.1 — 15.0 Adduct A1 33.1 — 33.1 — Adduct A3 — 35.1 — 35.1 IPDA — — 17.0 17.0 Benzyl alcohol — — 20.0 20.0 Ancamine ® K54 — — 2.0 2.0 Viscosity (10′) [Pa ⁇ s] 0.66 0.75 0.82 0.92 Gel time (h:min) 3:40 3:40 3:10 3:20 Shore D (1 d SCC) 79 78 75 77 (2 d SCC) 80 79 77 78 Shore D (1 d 8°/80%) 23 38 31 38 (2 d 8°/80%) 58

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• 2021
  • 2021-07-28 EP EP21188304.6A patent/EP4124631A1/de not_active Withdrawn
• 2022
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